<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>自定义函数与调用</title>
</head>
<body>
    <script>
        //求n~m 之间所有数的和
        //n , m 形式参数（形参）
        function getSum(n,m){
            var sum = 0;
            for(var i = n; i<=m ;i++){
                sum += i;
            }
            console.log(n+ '~' + m+ '之间的数相加为：' + sum);
        }
        getSum(5,10);// n = 5, m =10 sum =0+ 5+6+7+8+9+10 = 45
        getSum(100,1000);//n= 100, m =1000; sum = 0+100 +101 + ...+1000=495550
    </script>
</body>
</html>